1. Field of the Invention
The present invention relates to a method and apparatus for cleansing, rejuvenating, or restoring polluted substances. More specifically, the invention relates to a universal method and apparatus for cleansing, rejuvenating, or restoring contaminated or polluted substances such as contaminated soil, sand or sludge which may be produced by leaking gasoline or diesel fuel oil storage tanks, or by industrial processes. Whether the contaminated substance is such as soil found at an abandoned storage site, or sludge from an industrial operation, the contaminated substance must be restored to make the land upon which it was found, or the substance itself, suitable for some other use. Heretofore, the clean-up costs could easily be more than the market value of the item involved.
2. Description of the Prior Art
The need for clean-up of polluted soils, or the restoring of sludges produced by industrial processes and their conversion into useable materials, is a rather recent phenomenon. Heretofore, these operations have been very expensive and time consuming. One soil clean-up method known in the art has been to spread out the contaminated soil and mix it with an absorbent substance. The absorbent substance binds the heavy metals in the polluted soil. The mixture of polluted soil and absorbent is manually sprayed with hydrogen peroxide, and the soil is again mixed using suitable implements. The peroxide reacts with the remaining contaminant in the soil to form reaction by products which are more environmentally acceptable. However such manual method has proved to be extremely expensive, and only suitable for a single purpose. Therefore, those in the art sought a better solution to the problem.
One such method and apparatus is such as described in U.S. Pat. No. 4,927,293 issued on May 22, 1990 to Randy P. Campbell. This method and apparatus involved placing the contaminated soil on a conveyor, applying an absorbent to the soil, receiving the contaminated soil and the absorbent materials at a transfer location, and concurrently mixing the materials together and transporting them from a transfer location to a deposit location while applying an oxidizing material to produce a reaction having more acceptable by-products. To enhance the reaction, air under pressure was introduced as the material was being mixed and transported to speed up the reaction. The exhaust air was then passed through collectors to capture any volatile, gaseous, reaction products.
However, this method and apparatus, although mechanized, proved to be rather slow. It was still only a single purpose apparatus, and was usable only with one particular treatment process. Also, it was found that the introduction of air under pressure intensified the oxidizing reaction to such an extent that sometimes dangerous conditions could prevail in the apparatus. In addition, since the power supplied to drive the aerator was in no way connected to the hydraulic system used to operate the remainder of the system, on at least one occasion when the blower was shut down, air continued to be injected, and an explosion resulted because the reaction by products built up.
Thus, the aforementioned method and apparatus, while being somewhat satisfactory, still did not solve the problems present in the soil treatment art, presented safety problems, and was still a single purpose device. Therefore, those skilled in the art, including Applicants, continued work toward finding a better solution.
Applicants undertook a careful study of the problems present in the soil treatment art, including a study of the aforementioned process, with a view to developing a method which would not only be suitable for soil treatment, but could also treat contaminated items or polluted substances such as desert sands and industrial sludges. In addition to developing such a multi-purpose method and apparatus, applicants were determined to develop a faster and more economical method and apparatus than was heretofore available. Applicants, after careful study of the problem, were able to adapt a portable mixer of their manufacture, called the MOBIL-CRETER.TM., manufactured by them for 17 years, to the treatment of polluted substances. The MOBIL-CRETER was particularly adaptable because it had an inclined auger which applicants found enabled them to speed up the oxidation process of the previous apparatus. Because the mixing and conveying apparatus previously described operated in a horizontal plane, the soil would quickly travel from one end to the other end of the mixing and conveying apparatus and the mixing and conveying device had to be run very slowly for the oxidizing process described in U.S. Pat. No. 4,927,293 to sufficiently take place to cleanse the soil.
By using the well-known properties of an auger, and using the inclined auger of their previous apparatus, Applicants were able to process much more dirt by in effect lengthening the path of travel which the dirt or polluted substance took after being sprayed with the oxidizing material. Only after travelling several times to near the top of the auger, and then falling back because of the soil being of too large a particle size, would the soil eventually be broken down into small enough particles to travel completely to the top of the auger and be discharged at the output. However, this method and apparatus known in the art still had serious limitations. By the time such apparatus was developed, several proprietary processes were developed by chemical manufacturers. Yet, no one method and apparatus could be used with all the proprietary processes. In addition, the apparatus was still only a soil treatment apparatus, and could not treat other polluted substances such as industrial waste. As a result, a need still existed to provide for a universal method and apparatus for treatment of all types of polluted substances in a speedy and improved manner.